This invention relates to the synergistic improvement of nylon molding compositions whereby higher Izod impact resistance is obtained in molded objects prepared from such nylon compositions.
It is known (U.S. Pat. No. 3,388,186 of June 11, 1968 to Kray et al.) that compositions of nylon-6, containing ethylene copolymer having a minor proportion of acrylic or methacrylic acid or alkyl ester thereof as backbone and having grafted polycaproamide side chains, show higher impact resistance than nylon-6 molding compositions not containing the above graft copolymer. The patent shows also lesser improvement in the Izod impact resistance of molded articles wherein nylon-6 is dry blended as major ingredient with an ethylene copolymer containing a minor proportion of such acid or ester as comonomer, and the blended mixture is extruded from the melt. These ethylene copolymers contain between 1 and 20 mol percent of the minor comonomer.
U.S. Pat. No. 3,472,916 of Oct. 14, 1969 to Anspon et al. discloses blends of 70-98% by weight nylon-6 homopolymer with correspondingly 2-30% by weight of ethylene/acrylic or methacrylic alkyl ester copolymer, having improved Izod impact resistance, compared to nylon-6 alone. The alkyl group in the alkyl ester copolymer contains 1-4 carbon atoms and the alkyl ester is from 10 to 60 percent by weight of the copolymer. The copolymer has "highly uniform distribution of the acrylic ester in the copolymer", presumably a random distribution.
U.S. Pat. No. 3,963,799 of June 15, 1976 to Starkweather shows ternary blends of polyamide, polyethylene or copolymer thereof, and a small amount of copolymer having ethylenic backbone and polycaproamide side chains.
French Pat. No. 1,386,563 of issue date Dec. 14, 1964 relates to compositions of 50-99 percent by weight polyamide and the balance an olefin copolymer containing up to 10 mol percent of acid side chains.